The present invention relates to a variable speed pulley system for transmitting power from one location to another. In particular, the present invention relates to a pulley plate for use with an opposing pulley plate having a belt disposed therebetween. The pulley plate includes a belt-wiping surface or feature obliquely extending from the pulley plate""s inner surface and located so as to engage the belt and to remove debris.
Variable speed pulley systems are used for transmitting power from one location to another in applications requiring an adjustable drive ratio between a drive shaft and a driven shaft. The pulley systems are typically powered by an engine or other drive mechanism. As conventionally known, variable speed pulley systems may be used to drive a multitude of secondary mechanisms for performing a variety of different functions.
Variable speed pulley systems usually include a drive pulley, a driven pulley, and a belt. The drive pulley generally comprises two pulley plates, one of which is anchored and the other of which is movable with respect to the anchored pulley plate. The belt extends from between these two plates on one end to some distal pivot, which may be another sheave comprising two spaced apart pulley plates and a torque sensing unit for accommodating fluctuating loads. The torque sensing unit, as described in U.S. Pat. No. 4,173,155 issued to Togami et al, reacts to a quick change in the load applied by the belt (for example, in response to a large mat or quantity of material entering a threshing mechanism).
Each pulley plate of the drive and driven pulleys has a face that encompasses a pulley contact surface. The pulley contact surfaces of two pulley plates of either the drive or driven pulley face one another. The pulley contact surfaces are generally angled so that as the distance between the pulley plates is reduced, the belt is forced into contact with the faces of the plates at a greater spacing from the center of the faces. Conversely, as the plates are moved apart, the belt is allowed to contact the faces of the plates at a smaller spacing from the center.
Many of the machines employing a pulley system as a component, such as agricultural and construction equipment, are subject to large amounts of dirt, dust and chaff which fills the air and becomes deposited upon the pulley plates and the belt. This problem is of special concern in harvesting machines such as combines where the harvesting machine itself generates a large volume of chaff during the harvest of crops. The dirt, dust and chaff which become deposited upon the pulley plates reduce the coefficient of friction between the pulley plates and the belt causing the belt to slip and heat up. As a result, the dust, dirt and chaff deposited upon the pulley plates and the belt reduce belt life and reduce power transmission efficiency. Variable speed pulleys and pulleys used in conjunction with torque sensing devices have an additional problem in that the engagement between the pulley plates and the belt occurs over a small surface area. Consequently, even in a clean environment, it is desirable to increase the friction between the plates and the belt in order to achieve greater power through-put values.
Thus, there is a continuing need for a device that removes debris from the belt and increases the friction between the pulley plate and belt of a pulley system without requiring dismantling of the pulley system.
According to one exemplary embodiment, a pulley for use with a belt includes a first surface, a second surface facing the first surface, and a first plurality of belt-wiping grooves in the first surface. The first and second surfaces are adapted to rotate about an axis extending through the first and second surfaces. Each of the first and second surfaces includes an outer perimeter. The first plurality of belt-wiping grooves in the first surface extend at least partially between the axis and the perimeter and are unequally circumferentially spaced from one another.
According to another exemplary embodiment, a pulley for use with a belt includes a first surface, a second surface and a plurality of belt-wiping grooves in the first surface. The first and second surfaces are spaced from one another to receive the belt and are adapted to rotate about an axis extending through the first and second surfaces. Each of the first and second surfaces includes an outer perimeter. The plurality of belt-wiping grooves in the first surface extend at least partially between the axis and the perimeter and are centered about a center offset from the axis.
According to another exemplary embodiment, a pulley plate for use with an opposing pulley plate so as to receive a belt therebetween includes an inner surface adapted to face the opposing pulley plate and a plurality of belt-wiping grooves in the inner surface. The inner surface has an outer perimeter and a first center about which the pulley plate is adapted to rotate. The plurality of belt-wiping grooves in the inner surface extend at least partially between the first center and the perimeter. The plurality of belt-wiping grooves are unequally circumferentially spaced from one another.
According to another embodiment, a belt drive system includes a drive pulley, a driven pulley, and a belt. The drive pulley includes a first inner surface and a second inner surface facing the first inner surface. The first and second inner surfaces are spaced to form a first recess and rotate about a first axis extending through the first and second inner surfaces. The driven pulley includes a third inner surface and a fourth inner surface facing the third inner surface. The third and fourth inner surfaces are spaced to form a second recess and rotate about a second axis extending through the third and fourth inner surfaces. The belt is received within the first and second recesses to connect the drive pulley to the driven pulley. At least one of the opposing inner surfaces includes a perimeter and a plurality of belt-wiping grooves unequally circumferentially spaced from one another.